U.S. Treasuries extended price gains on Wednesday, with the 30-year bond rising over a point after a $29 billion auction of seven-year notes saw strong demand.

Indirect bidders, which typically include buying by foreign central banks, took 64.2 percent of the debt on offer, the highest since June 2009, analysts said.

Dealers, who took in around 58 percent of debt offered in auctions on Monday and Tuesday, bought only 31.2 percent of the notes on Wednesday.

It went extraordinarily well, said Jim Vogel, interest rate strategist at FTN Financial in Memphis, Tennessee. The seven-years captured everyone's imagination right here.

The seven-year notes were sold at a high yield of 2.83 percent, which is lower than where they were trading ahead of the auction.

The most liquid seven-year notes were last up 25/32 in price to yield 2.74 percent, down from 2.88 percent late Tuesday.

U.S. benchmark 10-year Treasury notes last traded 29/32 higher in price to yield 3.37 percent, down from 3.49 percent late Tuesday.

Thirty-year bonds were trading 1-19/32 higher in price to yield 4.44 percent from 4.54 percent.